In a gas-phase polymerization process, traditional Ziegler-Natta catalysts have been shown to readily polymerize ethylene with one or more higher alpha-olefin comonomers such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 3,5,5-trimethyl-hexene, to produce a linear low-density polyethylene (LLDPE) with minimal if any long-chain branching (LCB). The increasing development of metallocene catalyzed olefin polymers has resulted in the ability to produce similar polymers with a more well-defined molecular structure than can be achieved with conventional Ziegler-Natta catalysts . Metallocene linear low density polyethylenes made according to U.S. Pat. Nos. 5,420,220 and 5,324,800, for example, possess narrow comonomer and molecular weight distributions. U.S. Pat. Nos. 5,527,752 describes further a family of metallocene catalyst precursors which are useful, when combined with a cocatalyst or catalyst activator, in the manufacture of polyolefins.
The various linear low density polyethylenes referred to above are known to be useful, among a wide variety of applications, in those applications in which a crosslinkable polymer is requited.
In this vein, industry has been seeking polymers, which have improved crosslinking properties without sacrificing processability.